Display auth buttons depending on instance configuration => DONE, Fix tests => DONE

karma.conf.js

package.json

src/app/core/components/nav.component.html

src/app/core/components/nav.component.spec.ts

src/app/core/components/nav.component.ts

src/app/core/containers/app.component.spec.ts

src/app/core/navigation.guard.spec.ts

src/app/core/navigation.guard.ts

src/app/metamodel/model/instance.model.ts

src/app/shared/validator/nan-validator.directive.spec.ts

src/app/shared/validator/range-validator.directive.spec.ts

src/settings/test-data/instance.ts

yarn.lock